The effect of altitude on the boiling point of water is that it decreases with rising altitude. At higher elevations, atmospheric pressure is lower, causing water molecules to require less energy to escape as vapor. This results in a reduction in the boiling point of water; for instance, at sea level, water boils at 100°C, while at 2,000 meters altitude, it may boil at around 93°C. This phenomenon is significant in cooking, scientific experiments, and understanding climate variations in different regions.